The present invention is directed to a real time radiographic inspection system for testing articles such as production parts or assemblies. While the invention will be disclosed herein with specific reference to the use of such an inspection system for inspecting an airbag inflator for an automotive vehicle airbag, it should be appreciated that the invention may also be utilized for the inspection of other articles, such as production parts or assemblies.
It is often desirable in the production process of various parts and assemblies to provide for an online testing or inspection of the part, assembly or subassembly at various stages prior to further processing. Elimination of unacceptable parts or assemblies at appropriate points in the production process is often highly desirable in automated high volume, high speed production operations. In order to maintain the efficiency of the process, it is desirable that such inspection or testing take place in the actual production line without requiring removal and replacement of parts in the line and without appreciably slowing the production process. Thus, cycling of parts for testing or inspection and the entire test or inspection cycle should preferably be maintained in the production line without interfering with the production equipment itself, its placement in the line or the operational speed of the production process or line.
In the case of real time radiographic (RTR) inspection, a number of benefits, but also a number of shortcomings, have been experienced with prior art equipment and methods. For example, real time radiographic testing involves the X-ray imaging in real time of the articles, such as parts or assemblies, to be inspected. Criteria can be established for judging the acceptability or unacceptability of the images produced by such a system, such that unacceptable articles can be removed from the production process at an appropriate point. The use of appropriate data processing equipment in connection with such imaging can further store data corresponding to such images and the records of tested articles for later verification, for recall purposes, or the like.
The use of X-ray imaging equipment requires the provision of an appropriate shielded enclosure or housing for the imaging equipment. This requirement in turn leads to a requirement for automated handling of the articles which are to be tested inside of the housing to accomplish the individual X-ray imaging of the articles without physical entry of an operator into the housing. These requirements have lead to a number of problems with the prior art real time radiographic equipment.
For example, it is desirable that the article handling equipment within the X-ray enclosure consistently handle and position each article relative to the X-ray beam to assure consistent imaging results for all tested articles. It is also desirable that this article handling system be relatively simple, rugged and reliable and relatively easy to realign or repair. Similarly, it is desirable to maintain the proper geometry of the X-ray components to assure the consistent production of an acceptable and consistent image for each article. In this regard, it is also desirable to provide for relatively fast and simple adjustment of the alignment of the X-ray components and preferably, the X-ray equipment should be capable of real time, "X-ray on", image alignment.
As a further matter, the X-ray image should preferably also be visually inspectable to verify the acceptability or unacceptability of the article, such as a part or assembly, being tested. As a related matter, it is desirable that the X-ray components be relatively reliable and have low down time, being relatively easy to access for repair as necessary, so as to minimize interference with the production process.
As a still further matter, it is also desirable that the real time radiographic inspection system and components, including its enclosure, be relatively easy to assemble, and be capable of performing on-line testing (without removing the articles from the line) on existing production lines or conveyors and related machinery and equipment, without requiring extensive redesign and reconstruction of the existing production line. It is also desirable that the equipment take up as little floor space as possible, because floor space is generally at a premium in high volume, high speed production facilities. As a related matter, it is desirable that the real-time radiographic (RTR) systems, including its enclosure, be relatively simple and easy to disassemble and reassemble to service another location or accommodate modifications to the production process and equipment.
Generally speaking, the prior art real time radiographic (RTR) systems for inspecting inflators have not always provided all of the foregoing desirable features. For example, with respect to the article handling and positioning systems, prior art real time radiographic test instruments utilized a que system. This que system would mechanically present a predetermined amount of product to the real time radiographic test instrument. In order to que product, the prior art system would remove the product from the normal process line and introduce it into a separate, machine X-ray enclosure. This que system required a number of sophisticated mechanical systems, such as sets of tooling to position the articles, an index table, a complex three-part gripping system and a complex product entrance and exit system with respect to the X-ray enclosure.
The use of such complicated parts and systems multiplies the number of areas in which malfunction can occur resulting in disturbance of the production process, or in misalignment or inconsistent handling of articles, resulting in inconsistent test results. The requirement that the articles be removed from the production process to accomplish the test can also interfere with the production process, by using a relatively cumbersome system for removal and reintroduction of parts or articles with respect to the production process.
The prior art RTR inflator inspection systems have provided relatively cumbersome and complex internal article handling components and arrangements in which it has been difficult to maintain consistent alignment for consistent imaging by the X-ray beam. Real time, "X-ray on" image alignment was not possible. Some of these prior art systems have utilized relatively complex servo-motor alignment components, which never quite achieve the same positioning of an article relative to the X-ray beam from one article to another. Moreover, both the handling and X-ray imaging parts of the prior art systems had generally been designed such that they are relatively difficult to access, and difficult to adjust, realign or repair, requiring excessive down time in the production cycle to accomplish such adjustment, realignment or repair.
With respect to the enclosures or housings of prior art machines, these were generally designed around the articles and the relatively complex handling systems discussed above. This in turn usually created a relatively large, heavy cabinet that would be difficult to relocate and would limit machine reconfiguration, making all but the most simple changes very difficult or even impossible. Generally such cabinets were assembled by welding or similar means, such that they could not readily be disassembled for relocation, for example, to be redeployed at different points in the production process, or reconfiguration, for example, to accommodate redesign of the production equipment. As an additional matter, these prior art enclosures or housings were also generally quite large, owing to the large amount of space necessary for the extensive and complex article handling equipment to be housed therein, thereby taking up large amounts of factory floor space.
With respect to reject systems of the prior art, similar considerations apply as those discussed above with respect to article handling in general. Prior art systems generally used relatively complex article handling arrangements for removing failed articles following the completion of real time radiographic testing. These relatively complex handling systems also required relatively large amounts of floor space, were relatively expensive and inefficient and difficult to debug or troubleshoot, requiring extensive system down time to effect repairs.